Abstract: In order to understand the status and evolution trend of fertility of paddy soils in Tonglu county, Zhejiang province, historical changes in soil pH, organic matter, available P, available K of the cultivated layer were analyzed over the past 30 years by comparing data obtained from the current soil quality investigation of cultivated lands and the second national soil survey. The results showed that those soil fertility indexes of cultivated layer of paddy soils in the county changed greatly in the past 30 years, but the direction and degree of the change varied with nutrient types and zones. The soils were slightly acidified, and averaged pH declined 0.07 pH unit. The soil cation exchange capacity of paddy soils in the county was at low level. The organic matter of the soils was significant decreased by 17.32%. The decrease proportion of soil organic matter in Fenshui town was 24.17%, and was the largest in the whole county. The available phosphorus and potassium were significant improved by 173.75% and 63.05%, respectively. The soil available P has emerged accumulation phenomenon in some area. The most obvious accumulation appeared in Tongjun town, and it was increased by 316.24%. The available K was also remarkable improved, but it was still at a moderate level, and Tongjun town was increased by 112.62%. The changes in soil fertility of paddy field in the county were relate to the changes in fertilization structure and cropping system in the past 30 years.

Key words: Tonglu County, paddy soil, fertility, evolution

摘要： 为了解浙江省桐庐县稻田耕层土壤肥力现状及其演变趋势，利用历史资料和近期地力评价调查数据，探讨了近30年来桐庐县稻田耕层土壤主要肥力指标的变化特征。结果表明，近30年来，桐庐县稻田耕层土壤主要肥力指标发生了较大变化，但变化方向和变化程度因养分种类和区块而异。土壤pH值有轻微的酸化趋势，平均降低0.07个pH值单位；土壤阳离子交换量总体上以中低水平为主；土壤有机质显著降低，平均降幅为17.32%，以分水区块下降最为明显，降幅为24.17%；土壤有效磷和速效钾显著提升，平均增幅分别为173.75%和63.05%。其中，土壤有效磷已出现了累积现象，以桐君区块累积最为明显，增幅高达316.24%；土壤速效钾虽提升显著，但仍处于中等水平，桐君区块提升最多，增幅为112.62%。分析认为，施肥结构和种植制度的改变是引起桐庐县稻田土壤肥力变化的主要原因。

关键词: 桐庐县, 稻田土壤, 肥力, 演变